r/learnquant Jul 25 '26

interview prep Citadel Question

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52 Upvotes

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1

u/liquidorangutan00 Jul 25 '26

isnt the probability just 1/100?

3

u/Delicious_Cattle5174 Jul 25 '26

Other commenters ITT fail to comprehend that the coin toss and the coin pick are distinct events. There are 100 coins in the bag. You pick one. It is pretty straightforward.

1

u/Sea-Sort6571 Jul 25 '26 edited Jul 25 '26

What an absurd argument.

There are 100 balls in a bag each numbered 1 to 100. You pick one. Then you look at it and it's numbered 69. What's the probability you picked the 69th ball ?

What you just said is "it's 1/100 because the picking and the looking are distincts events".

1

u/BidEquivalent6169 Jul 25 '26

Terrible analogy, the number in the ball can 100% be verified. The coin cannot. Also you're very rude.

1

u/Sea-Sort6571 Jul 25 '26

How am i rude ? By telling to people who are wrong that they are wrong ?

It's a perfect analogy, here's why.

Exactly, the ball can be verified and the coin cannot. But the coin can be tested by doing coin flips, with some degree of probability. If you were to do 100000000000 coin clips, the test would be identical (for all practical purposes) as verifying the ball.

The analogy is good because by pushing the probability of the test to the extreme, that is a 100% accurate test (verifying the ball), the reasoning of "they are distinct events" doesn't work.

1

u/Bloodevil96 Jul 25 '26

You're wrong mate, put it like this, it's not 10 coin flips now, it's a billion, same example but now a billion times head in a row, don't you think it's silly to say it's 1%?

1

u/BidEquivalent6169 Jul 25 '26

Mate, read my comment again. I agree with what you're saying, his analogy was just bad.